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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><o:p> </o:p></p><p class=m2994880643397275864m2777798639370925255xmsonormal><b><span style='font-size:16.0pt;font-family:"Arial",sans-serif'>In the Washington Post today in Outlook, Mr. only humans count, made many mistakes of course. I would like to start with his summary of mass extinctions that “come every 50 million to 100 million years, and scientists agree that we are now in the middle of the sixth extinction, this one caused primarily by humans… the sixth extinction will be followed by a recovery, and later a seventh extinction, and so on.” We should read the scientific literature on mass extinctions. The first mass extinction eliminated two thirds of the fundamental basic forms of life forever. Over all there is a threshold level of degree of damage from mass extinction so that for some there is recovery, although it takes millions of years, and above that threshold there is not recovery. Studies have shown that with our current conservation efforts we can keep the sixth extinction below that threshold, but only if we continue that effort. So set aside natural areas making sure that keystone species are kept there. For example, the keystone crayfish burrows in wetlands that freeze over, support about a dozen aquatic species about a foot or two below ground level because the temperature is about 50 degrees (symbiosis). When the endangered species Act of 1973 was passed studies showed that new species evolved at le<span style='color:#1F497D'>ss</span> than 1 percent of the rate they were becoming extinct, because of us. Responses to that Act has helped a lot. Host specific, effective<span style='color:#1F497D'>,</span> biological controls of non-native species has helped a lot. Japanese Knotweed is no longer as bad a problem that it was in Great Britain as a result. Cheers </span></b><o:p></o:p></p><p class=m2994880643397275864m2777798639370925255xmsonormal><b><span style='font-size:16.0pt;font-family:"Arial",sans-serif'> </span></b><b><span style='font-size:18.0pt;font-family:"Arial",sans-serif;color:#1F497D'>Marc Imlay, PhD</span></b><o:p></o:p></p><p class=m2994880643397275864m2777798639370925255xmsonormal><b><span style='font-size:18.0pt;font-family:"Arial",sans-serif;color:#1F497D'>MD Chapter, Sierra Club, Natural Places Working Group Chair </span></b><o:p></o:p></p><p class=MsoNormal><b><span style='font-size:16.0pt;font-family:"Arial",sans-serif'><o:p> </o:p></span></b></p></div><div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2">
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